Frequently Asked Questions

If your parallel port display does not work, please run lcd4linux -Fvv and have a look at the output. if you get these messages:

HD44780: using ppdev /dev/lp0
HD44780: ioctl(/dev/lp0, PPCLAIM) failed: 22 Invalid argument
HD44780: could not initialize parallel port!
HD44780: start display failed!

then you did not read the documentation, because there it reads:

Note that you have to use parport devices (usually /dev/parports/* or /dev/parport* with major number 99), the printer devices (/dev/printers/* or /dev/lp* with major number 6) do NOT work!

So you have to change your lcd44linux.conf and replace the Port '/dev/lp0' with Port '/dev/parports/0'

If you don't have that you'll need to create it first with 'mknod /dev/parport0 c 99 0'.

not approved yet Of course, you have to had permission to use /dev/parport0 For some reason, changing the permission with chmod do not hold after a restart on some distribution. Instead, you should just make sure the user that runs the program is in the lp group. not approved yet

If you get the message “usb_claim_interface() failed”, you probably do not have sufficient user rights to access your display. Here's how to solve it on Debian based systems that use “udev”:

1. create the group “lcdusers” by running

# sudo groupadd --system lcdusers

2. add yourself to this group

# sudo usermod --append --groups lcdusers your_username

3. find the “idVendor” values for your display (in this case “04d8” and “c002” for the “picoLCD 256×64”):

# lsusb
Bus 003 Device 002: ID 04d8:c002 Microchip Technology, Inc.

4. create the file “/etc/udev/rules.d/60-lcd.rules” with the following contents (you'll of course have to change the “idVendor” and “idProduct”):

SUBSYSTEM!="usb_device", ACTION!="add", GOTO="lcd_rules_end"
# picoLCD
SYSFS{idVendor}=="04d8", SYSFS{idProduct}=="c002", GROUP="lcdusers", MODE="0660"

5. it might be necessary to reboot your system. Then run “ls -l /dev/usb/” to verify that your display is in the “lcd_users” group:

# ls -l /dev/usb/
total 0
crw-rw---- 1 root lcdusers 180, 96 2010-01-20 13:55 hiddev0

6. enjoy your new display… :)

Not all plugins works well with cygwin:

./configure --with-drivers=VNC,NULL --with-plugins='all,!dvb,!i2c_sensors,pop3'

Now it works like a charm…

  • faq.txt
  • Last modified: 2020/07/17 18:33
  • (external edit)